"Our researchers have identified a reputable seller, who is selling 47.5 million Indians Truecaller records for USD 1,000 (about Rs 75,000). The data is from 2019. We were also taken off by surprise with such a low price point," Cyble said. The data on sale includes phone numbers, gender, city, mobile network, Facebook id etc.

"Accenture has no professional relationship with Unacademy, and any implication or assertion otherwise is erroneous. Accenture has suffered no data breach or loss of any records or client information as a result of this incident," Accenture said in a statement.

Ransomware is a type of malicious program used by hackers to take control of files in an infected system and then demand hefty payments to recover them. The Maze ransomware was discovered in 2019 and has since gained notoriety.